I wanted to win a science victory right after winning a cultural victory. To win a science victory, I have to build a bunch of spaceship parts and move them to my capital, where they are assembled. Thing is, I can't stack units, so either the spaceship parts can't move to the capital if there is another part there, or they just switch spots. Is this normal, or it is a bug?

To construct the spaceship, whenever you move a spaceship module to the capital, you need to choose the option to "add" it to the spaceship. The module will disappear and your spaceship will receive it (if it's the first module you add, a 3D model of a spaceship will also appear near the city). This option should be listed at the command bar on the left, just like other unit options.

However, you cannot add modules to the spaceship if one of these applies:

Another civilization has already completed a spaceship

You have manually disabled the "science victory" option when you set up the game

You have already won the game in some other way

As you can see, the 3rd case above applies to you. I'm afraid you cannot conquer the stars in this game... you have no choice but to start another :) enjoy your all-nighter!

Upvoting this gives mixed feelings. It's a good answer, but I really dislike that the science victory is the only one disabled after you already win. I wish they would change it. I was going for science victory but accidentally won by the diplomatic victory way before I was even able to build the space parts (it was in 1946, and I now have all parts in 1983 - having won culturally as well, in between). I was so excited to see the science victory for myself. Now I guess I'll have to sell them for the 4 aluminium: i.imgur.com/AMZN4By.jpg
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Aske B.Apr 16 at 1:35